Field of the Invention
The invention is directed to non-homopolymers that are polymerized from at least four polymerizable monomers. In one embodiment, the polymers are soluble in at least one lower molecular weight alcohol such as methanol, ethanol, 1-propanol, or 2-propanol.
Description of Related Art
Formulation scientists often face multiple challenges when developing new or reformulating existing products. Many times, products must attain target attributes that can only be achieved by one or more polymers, properties like UV absorption, adhesion, shine, smoothness, texture, binding, and/or water solubility/insolubility profile. For optimal performance, the polymer(s) must be soluble in an amenable solvent system, either during product formulation or end use. Due to its low toxicity, cost, and boiling point, ethanol and other low molecular weight alcohols are a solvent of choice for many products, especially cosmetics for use on the skin or hair.
Unfortunately, there is a limited selection of polymers soluble in lower molecular weight alcohols that also exhibit advanced functionality required for next-generation products. For example, while poly(vinyl alcohol) demonstrates excellent film strength, it flakes easily. To overcome these solubility and/or property deficiencies, polymers are often engineered as non-homopolymers to exploit the benefits of two or more monomer units. However, the polymer scientist must balance sometimes competing constraints between performance and solubility. Hence, needed are polymers that are soluble in the lower molecular weight alcohols which also satisfy the demands of product performance.
The related art teaches various polymers used in the cosmetic arts and their uses. Representative U.S. patent applications include 2002/0076390, 2002/0146515, 2004/0132863, 2005/0065252, 2005/0222322, 2005/0265949, 2007/0086959, 2010/0080763, and U.S. Pat. Nos. 4,486,577; 4,508,884; 5,662,892; 5,912,294; 6,126,929; 6,686,413; 7,048,916; 7,122,175; and 7,144,928. These publications teach polymers of differing compositions for use in applications ranging from cosmetics (e.g., hair, skin, nails) to floor polish and contact lens.
An acrylic resin is taught in U.S. patent application 2005/0065252 that is derived from a C1 to C14 (meth)acrylate, a 5- or more-member heterocyclic monomer, and a monomer having at least two olefinic double bonds. Composition [7] in this application is a polymer derived from a C1 to C14 (meth)acrylate, a 5- or more-member heterocyclic monomer, an alicyclic monomer, and a monomer containing at least one polar functional group such as a hydroxyl group. However, given the broad range in stated monomer levels, there is no indication that polymers of the '252 patent application should be ethanol soluble.
Personal care polymers are the subject of U.S. patent application 2002/0076390. The polymers are derived from 10%-85% (w/w) hydrophobic first monomer that is a (meth)acrylate of a C4 to C18 alkyl alcohol, 10%-70% (w/w) of a hydrophobic second monomer that is (meth)acrylate ester of a cyclic alcohol containing 6 to 20 carbon atoms, and up to 20% (w/w) of an optional hydrophilic third monomer, such as (meth)acrylamide, 2-ethoxyethyl(meth)acrylate or N-vinyl-2-pyrrolidone. The applications states, “The total amount of hydrophilic monomer preferably does not exceed about 20%, more preferably about 10% of the total weight of all monomers, such that excessive hydrophilicity is avoided.” As a result of this composition, the application states the glass transition temperature (Tg) of the polymers is preferably less than 35° C. Example polymers in Table 1 of the '390 application have a Tg of 15° C. or less, which means they exhibit rubber-like properties at room temperature, and may be too soft and/or tacky for many applications.
Also related is U.S. Pat. No. 7,122,175, which provides a reshapable hair styling composition comprising a (meth)acrylate ester of a C4 to C18 alkyl alcohol, a (meth)acrylate ester of a cyclic alcohol, at least one hydrophilic monomer, and, optionally, other monomer units. The '175 patent teaches broad ranges for the prescribed named monomer units. The synthesis methods disclosed in this patent include emulsion polymerization in water with dodecyl benzene sulfonate, solution polymerization in methylethyl ketone followed by inversion in water, and suspension polymerization in water. Additionally, the polymer of Example 1 is taught as a hair styling composition in water. However, the '175 patent does not disclose the existence of alcohol-soluble polymers, let alone enable one skilled in the art how to attain them. Furthermore, the polymers that are taught possess low glass transition temperatures, about −100° C. to about 15° C., which can render them sticky and tacky at room temperature, and which realistically limits their usefulness in the cosmetic arts like skin, sun, and hair care products.
Despite the body of related work in polymer chemistry, there still exists a commercial and industrial need for polymers that are soluble in lower molecular weight alcohols, especially ethanol. Of particular value are alcohol-soluble polymers having a glass transition temperature greater than about 40° C. to enable their use in the cosmetic, adhesive, inks, and coatings arts.